A vehicle system includes a power electronics device and a coolant circuit thermally coupled to the power electronics device. The coolant circuit includes a fluidic pump and a fluid/air heat exchanger, an air pump configured to transfer air across the fluid/air heat exchanger, and a shutter device configured to control airflow across the fluid/air heat exchanger. A controller controls the fluidic pump to control coolant flow through the fluid/air heat exchanger to reject heat from the power electronics device to the coolant and correspondingly controls the air pump and the shutter device to control airflow across the fluid/air heat exchanger to reject heat from the coolant to achieve a preferred heat rejection from the power electronics device.